‘Given that we know Ian did have affairs,’ Kate said, picking her words very carefully, ‘was there something you thought particularly unusual about this one?’

‘The first of our marriage. The shattering of an illusion.’ Celia shook her head sadly. ‘But now I mention it, I have to admit it wasn’t that. He just wasn’t quite himself during the last six months in New York and I became convinced that he was going to leave me.’

‘Had you ever thought that before?’

‘No, and never since. Ian was extraordinarily good at compartmentalizing his life in that regard. These affairs were just sex to him, a bodily function like eating or sleeping. He always insisted our relationship existed on a higher plane than anything he had experienced before or would again. And I was fool enough to believe him.’

‘But if this woman was an exception,’ Callum asked, ‘the obvious question is, perhaps, why?’

For the first time, Celia looked annoyed. ‘How the hell should I know? Perhaps she did unusual things in bed.’

‘But you said affairs were just sex,’ Callum said. He glanced at Kate. Julie was still examining her feet with great intensity. ‘So had you considered the possibility that you were right in that judgement and something else was going on there?’

‘What do you mean?’

‘Just that a Czech intelligence official operating in New York in the mid-nineties might easily have begun her career in the days of the old Soviet Union. So it’s not a complete stretch to imagine she retained old loyalties and was tasked with trying to recruit an ambitious young officer like Ian to work for the Russians, is it? Perhaps one might even convince him he was going to be of great assistance to a new democratic Russia rising from the Soviet ashes.’

‘Most of the Czech diplomats I met hated the Russians.’

‘Yes,’ Kate said. ‘But I think Callum’s point is that perhaps it was not betraying you that Ian had on his mind – as you’ve said, that didn’t seem to cause him many dark nights of his soul – but his country, which, as you said at the start, would have consequences far beyond a divorce.’

‘I just don’t think he has it in him.’ Celia raised her hands. ‘I can’t say more than that. I mean, is it possible that was what he had in his mind during those last few months in New York? Yes, I suppose so. I don’t know if this stupid tart was some kind of honey-trap deployed by the Russians, but all I can repeat is that I don’t think he has it in him to be a spy for Moscow. He’s just not brave or stupid – or desperate – enough. And what would have been his motive?’

‘Perhaps, newly-wed, he didn’t want news of the affair to destroy his marriage,’ Julie said. For the first time, she was looking directly at Celia, as if determined somehow to defend Ian from charges laid by his ex-wife.